Method for making thermal insulated pipe



Jan. 17, 1956 A. H. ISENBERG METHOD FOR MAKING THERMAL INSULATED PIPE Filed May 3, 1952 m INVENTOR.

United States Patent METHOD FOR MAKING THERMAL INSULATED PIPE Alexander H. Isenberg, Woodside, Calif.

Application May 3, 1952, Serial No. 285,9% 6 Claims. or. 18-59) This invention relates to the making of thermal insulated pipe particularly of the type wherein a length of metal conveyor pipe is enclosed in a plurality of preformed end to end thermal insulating sections, the sections secured in tightly abutting relation and surrounded with a thick layer of solid pitch cast in place, in turn enclosed in a sheet metal outer casing.

This application is a division of my copending application Serial No. 689,539 filed August 9, 1946 which was granted as Patent No. 2,608,754.

The object of the invention of this application is to provide a method for effecting a more efficient and quicker assembly of the parts in making such insulated pipe.

Briefly described, the invention of the method comprises mounting on a conveyor pipe, a plurality of sections of preformed thermal insulation in end to end relation so that the opposite ends of the collective sections are adjacently spaced from opposite ends of a conveyor pipe, holding the sections at a stopped position adjacently spaced from one end of the conveyor pipe, applying force at the opposite end of the insulation sections to compact them together, securing them temporarily in the compacted relation, optionally wrapping the insulation circumferentially with a wrapping while so held, and, either as so wrapped, or without such wrapping, inserting the unit of conveyor pipe and thermal insulation thereon within an outer casing in spaced relation relative thereto and forming a moisture impervious layer in said space.

Particular features and advantages of this invention will appear in the following description, the steps of the method being illustrated by the accompanying drawing.

In the drawing:

Fig. 1 is a side view partly in section, showing an insulated pipe, broken in length, and progressively completed from the left to the right-hand end.

Fig; 2 is a cross section of Fig. 1 taken along the line 2-2 thereof.

Fig. 3 is a similar cross section to that of Fig. 2 but showing a modification in the means for clamping the insulation pusher apparatus to the pipe.

Fig. '4 is a reduced size plan view of the soft rubber ring used as an end stop for the molten asphalt as it is introduced.

To give a better understanding of the detailed description to follow, it may be said that in making such an assemblage before the present invention, a desired length of conveyor pipe 1 had applied over it a series of preformed tubular sections 2, 2' of thermal insulation, composed of any suitable material, though preferably consisting of the well known magnesia steam pipe insulating sections readily obtainable in all sizes in tubular and split or half tubular sections.

These sections are slipped over the pipe, or if split are applied from opposite sides, moved up as close as pos sible, and secured in place as by spirally wrapping circumferentially about them one or more layers of cloth or canvas 3 held in place by any suitable adhesive.

After this has been done the covered pipe is placed fa in. I Q

within a much larger sheet metal casing 4 and spacedly centered therein as by the use of suitable spacing spiders 5 previously applied at spaced intervals over the heat insulation 2 whereupon fluid molten asphalt pitch or similar pourable waterproofing compound is poured into the outer casing to fill the space and permitted to set to form a solid water seal 6 impervious to entry of moisture, the pitch extending substantially the length of the thermally insulated portion of the conveyor pipe. At its opposite ends, the conveyor pipe has a bare portion extending beyond the thermal insulation, and preferably extending beyond the outer casing, so that such extended ends may be connected to other similar pipe sections in a continuous conduit system. The fluid molten pitch which hardens at normal temperature is then poured, either through one open end of the casing with the other end plugged, or through holes in the casing with both ends plugged, the molten pitch being adapted to flow between the casing and insulation and allowed to harden in situ. The spacer members 5 being spiders, they have a web portion extending perpendicular to the axis of the conveyor pipe 1, the web having openings therethrough, so that the fluid pitch may flow longitudinally as well as flow circumferentially between the outer casing and the body of the insulation.

In the making of the assembly it is difficult to get a tight juncture of the end-to-end insulation sections to prevent heat radiation and loss, and one of the objects of the present invention is to overcome this difliculty.

Therefore in the present method of this invention for making the assembly, a disk flange or collar plate 7 is secured tightly as a stop member spaced adjacent one end of the conveyor pipe as by one or more set screws 8 passing through the hub *i" of the flange and impinging the pipe. This flange is preferably a trifle smaller than the outer diameter of the insulation sections 2 as indicated.

The insulation sections are all pushed up in aligned end-to-end relation in the direction of the fixed flange 7 by hand or hammer, and a second flange plate 9, similar to fixed flange '7, is placed on the pipe at the opposite end of the insulation and set screw 10 tightened lightly against the pipe for pressure-induced slidability thereon, the said plates preferably being of a little less diameter than the insulation so as to substantially cover the end faces of the insulation which contact said plates. The flange plates are eventually removable by loosening the said screws. After thus placing the fiange plates, a hollow sleeve or carrier Elli is slipped over the end of the pipe between said second flange plate and the end of the pipe adjacent thereto, and securely clamped to the pipe as bymeans of a lever handle screw 12. The sleeve or carrier may be of a split type ill shown in Fig. 3 wherein its two halves are pivoted together as at 13, and may be engaged over the pipe by opening the halves and suitably clamping them together upon the pipe, as by bolts 14 pivoted to one of the halves, as at 15, and passing into open slots 16 formed in the other half as indicate On this carrier sleeve is mounted two or more fluid operated power pistons 15!, the cylinders of which are indicated as at 17, and the piston rods at 118. The carrier sleeve is clamped to the pipe with the retracted piston rods in contact with flange plate 9, the piston rods being at opposite points if there are two, or equally spaced around the flange, if there are more than two.

In the drawing pistons are shown automatically retracted by coil springs 2d, and also provided with rearwardly extending piston rods 13 to function as a stop to preserve starting clearance within the cylinders.

The showing of the automatically retracting pressure pistons implies no limitations as it is only made for illustrative purposes, and it is to be understood that the plung er rods or piston rods 18 may be of the known diaphragm or bellows operated type.

The cylinders are connected to a source of fluid pressure, preferably compressed air, by means of hoses 21,

l, and a Y fitting 22 and through a control valve 23 at the end of a supply pipe or hose 24. The valve is provided with a pressure relief opening 25 to bleed the cylinders when the pressure is turned off by swinging the handle 26 from in line position to the right angle dotted position. The valve is shown in cross section with the pressure open to the cylinders.

Before turning on the pressure, set screw 10 of the collar flange is released, and when the pressure is applied the pistons will at once powerfully force the contacted flange 9, and the insulation sections longitudinally along the pipe into close end-to-end contact to any degree desired. The pressure is therefore axially longitudinal along the pipe, using the pipe itself as a pressure base at one end as. opposed to the stop plate 7 at the opposite end. This saves hammering the insulation to a considerable extent since, due to the reverse thrust of the hammer pressure, there is a thrust on the pipe in one direction simultaneously with the pressure thrust on the insulation in the opposite direction. The set screw 10 may again be tightened to hold all of the insulation sections temporarily in tight contact and valve 23 turned off and the pressure .apparatus removed if desired, or the pressure may be maintained while the canvas wrappings 3, if they are employed, are adhesively secured around the insulation sections 2, and the pressure later removed. If split sections of insulation are used each pair may be drawn tightly together by the usual straps used for the purpose, before the end forcing operation is employed.

After the assemblage is completely wrapped with the cloth or other wrapping 3 (or even without such wrapping), the assembly is fitted with a number of the spacing spiders, as indicated 5, and inserted in the sheet metal outer shell or casing 4. Instead of the spacers 5 being applied over the assemblage they sometimes are formed integral with short sections of the insulation 2 as well known, and not affecting the present invention as described.

After inserting the assemblage into the casing the fluid molten pitch or asphalt 6 is poured in as explained, and permitted to harden in situ. If the wrappings 3 have been used and the insulation sections satisfactorily locked thereby in tight end contact, the flanges 7 and 9 may be removed before placing the assemblage into the casing,

but it is preferred to leave the flanges in place until after the pitch has been hardened, since the fluid pitch, when solidified and hardened, is a powerful friction factor which aids in locking the insulated sections against endwise separation.

It is understood in the art that the insulation sections are not in any way adherent to the pipe 1 itself as the pipe must at all times be able to expand and contract linearly due to the extreme variations in temperature to which it may be subjected by the nature of the fluid, either hot or cold, for which it may be used.

Before casting the molten pitch into the casing space, one or both ends of the space between the insulation and outer casing must be plugged, since in regular installations several, or a great many, pipe lengths assembled as described, are joined at their ends in longitudinal succession as by welding the extending ends of the bare inner pipe 1, and thereafter locally covering the joint with insulation, pitch, and a short section of casing to make the thermal insulation, the moisture insulation (pitch) and the casing continuous. the poured pitch at a point somewhat within the outer opposite ends of the insulation members 2, a matter which has heretofore been troublesome to accomplish in the manner best suited to the later completion of the joints of successively joined conduit sections.

This difliculty has been overcome by the use of a rela- For this reason it is desirable to stop,

tively soft and pliable thick rubber ring 28, shown in Fig. 4, inserted through the open end of the casing prior to pouring the pitch. This ring may be split as at 29 if desired, to permit removal after the pipe joints have been welded, though generally it is a circumferential ring which is removed after the poured fluid pitch has been hardened in a section of pipe unit and before the two lengths of pipe are welded together. The ring is preferably somewhat larger in outside diameter than the inside of the casing 4 and snugly fits upon the outer circumference of the insulation and wrapping 3 if used, so that when the ring is pushed into place as indicated in Fig. 1 it will be concavely deformed as shown, and thereby form a concavely shaped end to the cast pitch, thereby making a better joint with the pitch used at the joint and also preserving a free bare end margin around the insulation 2 for joining with the wrappings of the joint insulation. Because the rubber ring is thick (about /2 inch is found satisfactory) and readily pliable, it conforms to the somewhat uneven surface of the insulation 2 or wrappings 3 and also to the seldom perfectly round interior of the casing 4. Before inserting the rubber ring it is preferably coated with a layer of siliceous or whitewash to prevent sticking to the pitch.

By the apparatus and method of handling above set out the production of such thermally insulated pipe is greatly facilitated and a 'more efficient product secured. than heretofore possible under the conditions obtaining in the commercial making and installing of such pipe.

Having described the invention, what is claimed as new and patentable is:

1. In thermally insulated conduits, a method of covering a conveyor pipe with thermal insulation, comprising aligning a plurality of preformed sections of thermal insulation on the conveyor pipe in end-to-end relation and sufficiently loosely circumferentially of the pipe to permit relative longitudinal slippage between the pipe and insulation sections, holding one end of the aligned insulation members spaced relative to an adjacent end of the pipe and stopped against farther movement towards said adjacent end of the pipe, applying pressure longitudinally at the opposite pressure end of the insulation to compact the sections of insulation in end-to-end relation, temporarily securing said sections compacted relatively against movement longitudinally, and while said sections are so compacted, permanently securing them against longitudinal relative separation, thereafter releasing the insulation sections from the longitudinal pressure thereagainst, and imperviously enclosing said conveyor pipe and compacted and secured insulation against contact with exterior moisture.

V 2. A method of the character described as set forth in claim 1 and which includes the steps of providing a pressure base secured to the pipe at the end of the insulation at which pressure is exerted and applying the longitudinal pressure on the insulation axially of the pipe between said pressure base and the opposite stopped end of the insulation.

3. A method for covering a conveyor pipe with insulation material as defined in claim 1 and including the step of holding the stopped end of the insulation over substantially the entire area of said stopped end of the insulation and applying the longitudinal pressure on the insulation over substantially the entire area of the pressure end of the insulation.

4. A method of making conveyor conduits which are thermally insulated and impervious to entry of moisture, comprising the steps of aligning a plurality of preformed sections of thermal insulation on the conveyor pipe in end-to-end relation and sutficiently loosely circumferentially of the pipe to permit relative longitudinal slippage between the pipe and insulation sections, holding one end of the aligned insulation members spaced relative to an adjacent end of the pipe and stopped against farther movement toward said spaced end of the pipe, applying pressure longitudinally at the opposite end of the insulation to compact the sections of insulation in end-to-end relation, temporarily securing said section compacted relatively against movement longitudinally, and while said sections are so compacted permanently securing them against longitudinal relative separation, and thereafter releasing the insulation sections from the longitudinal pressure thereagainst, forming circumferentially of the compacted insulation a circumferentially supported layer of a liquefied bitumen, and confining said bitumen at the ends thereof until it hardens in situ to a moisture impervious layer.

5. A method of the character described having the steps defined in claim 4 and which includes the step of providing a pressure base secured to the pipe at the pressure end of the insulation and applying the pressure 1ongitudinally on the insulation axially of the pipe between the pressure base and the stopped end of the insulation.

References Cited in the file of this patent UNITED STATES PATENTS 46,134 Perkins Jan. 31, 1865 753,959 Crump Mar. 8, 1904 1,454,243 McIndoe May 8, 1923 1,499,774 Headson July 1, 1924 r 2,405,021 Durant July 30, 1946 

